Sale Of The Century (lost NBC game show; 1969-1973)
Sale of the Century was a american quiz show that ran on NBC from September 29, 1969 to July 13, 1973. It was first hosted by Maverick actor Jack Kelly and then by former Chicago Cubs catcher Joe Garigiola. The show would be brought back two times in 1973 (two months after it's cancellation) and 1983. Although the later versions of the show exist in some compacity, the original run of the show has not been seen since it last aired.
Three contestants started with $25 each and get $5 for every correct but lose $5 for every wrong answer. At certain points in the game there would be attempts to persuade the contestant with the most money to buy a prize 10% or less than it's original value, sometimes another gift is added to the prize as an incentive. The winner could use his/her's tally they won in the game to but expensive prizes at cut rates or return the next day to try again. 
No episodes have surfaced since their original airings and are most likely destroyed, lost or disposed of. The exact number of episodes that aired are unknown, some sources say around 1,000 episodes. Alot of those episodes can't be accounted for although the accounts of some episodes can be accounted for via press photos,  leaked photos, audio recordings or photos used for merchandise (i.e. board games). Some accounted episodes have airdates of October 21, 1969, October 27, 1969, December 12, 1969, December 18, 1969, December 19, 1969, June 9, 1970, March 8, 1971, March 16, 1971, March 24, 1971, April 1, 1971, September 29, 1972, March 12, 1973, March 20, 1973, March 28, 1973, April 5, 1973 and April 13, 1973 but unnamed contestants. Some episodes have photos with contestants names but no airdates.